Many different devices and methods have been developed which use x rays or neutrons as probes to investigate the structural or chemical properties, or elemental constituents of a sample. A significant problem with many of these devices is their lack of ability to obtain sufficient radiation intensities. A lack of radiation intensity causes measurement times to be longer than desirable, and can result in increased experimental noise. In some cases, where the sample to be investigated is unstable, long measurement times are not possible. In commercial applications, where time is money, any means to decrease measurement times is desirable.
Known to the art are multiple-channel plates which use a single total external reflection to focus x-ray and neutron beams, see U.S. Pat. No. 5,016,267 to Wilkins. Also known to the art are multiple-channel, multiple-total-external reflection x-ray, gamma-ray, charged particle and neutral particle, including neutron, optics which are capable of capturing such radiation from a radiation source and focusing that radiation with high intensity onto a small focal spot. See, for example, U.S. Pat. No. 5,192,869 to Kumakhov. In addition to providing large intensity gains, these optics can also provide increased spatial resolution due to a small focused radiation spot size on the sample. However, accompanying the gain in intensity is a certain amount of beam divergence; the amount of divergence depending in large part on the physical geometry of the optic. For certain applications of multiple-channel, total reflection optics, such as x-ray diffraction, and x-ray and neutron scattering, it is desirable to have high intensity radiation beams accompanied by the ability to have control over the output beam's divergence. It is also possible to use multiple-channel, total-reflection optics to form diverging radiation beams. For this case, the ability to control beam divergence would also be desirable.
Well known to the art are radiation shielding schemes and beam stops. Some of these are adjustable. See for example Japanese patent number 56-30295 (A) to Tadao Kubota. Beam stop devices are typically made of radiation absorbing materials such as lead or steel, and for the case of neutrons, materials that also contain lithium. In most, if not all implementations, their function has been to limit the spacial extent of the radiation beam. With the above background, the subject invention provides a novel use of beam stops, or shielding used in concert with multiple-channel, total-reflection optics to control the beam divergence.